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Abstract:

A system and method for preparing a pelletized carbon black product is
provided. The system includes a source of a carbon black product from a
pyrolysis process. A mixer is in communication with the source of the
carbon black product. A binder oil storage tank is in fluid communication
with the mixer. The binder oil storage tank is configured to inject a
desired amount of a binder oil into the mixer to form the pelletized
carbon black product.

Claims:

1. A system for preparing a pelletized carbon black product, comprising:
a source of a carbon black product from a pyrolysis process; a pulverizer
in communication with the source of carbon black product, the pulverizer
configured to pulverize the carbon black product to a desired particle
size; a magnetic separator in communication with the pulverizer, the
magnetic separate configured to separate extraneous ferrous material from
the carbon black product and make the carbon black product substantially
metal-free; a classifier disposed between and in communication with the
pulverizer and the magnetic separator, the classifier configured to
selectively provide only the carbon black product of the desired particle
size to the magnetic separator; and a pelletization subsystem in
communication with the magnetic separator and configured to pelletized
the pulverized, classified, and substantially metal free carbon black
product.

2. The system according to claim 1, wherein the pelletization subsystem
includes a mixer configured to receive the pulverized, classified, and
substantially metal free carbon black product.

3. The system according to claim 2, wherein the mixer is one of a batch
drum mixer and a rollo-mixer.

4. The system according to claim 1, wherein the pulverizer is a roller
mill pulverizer.

5. The system according to claim 1, wherein the classifier is an air
classification unit.

6. The system according to claim 5, wherein the air classification unit
operates at rotor speeds from about 400 RPM to about 2,000 RPM.

7. The system according to claim 1, further comprising a product
collection cyclone disposed between and in communication with the
classifier and the magnetic separator.

8. The system according to claim 7, wherein the product collection
cyclone uses cyclonic action to separate the carbon black product from an
air carrier stream coming form the classifier, a centrifugal force
created by the cyclonic action throwing the carbon black product toward a
wall of the product collection cyclone, after which the carbon black
product falls into and is collected in a hopper located underneath an
area of the cyclonic action for feeding to the magnetic separator.

9. The system according to claim 8, wherein a rotary valve is disposed
between and in communication with the hopper of the product collection
cyclone and the magnetic separator for the selective batch feeding of the
carbon black product to the magnetic separator.

10. The system according to claim 7, further including a pulverizer
recirculation fan disposed between and in communication with the
pulverizer and the product collection cyclone.

11. The system according to claim 1, further comprising a pulverizer feed
bin disposed between and in communication with the source of the carbon
black product and the pulverizer.

12. The system according to claim 11, further comprising a knife gate
disposed between the pulverizer feed bin and the pulverizer, the knife
gate permitting a selective feeding of the carbon black product to the
pulverizer.

13. The system according to claim 1, further comprising a pellet bagger
in communication with the pelletization subsystem and configured to bag
the pelletized carbon black product produced therefrom for at least one
of handling, storing and shipping.

14. A method for preparing a pelletized carbon black product, comprising
the steps of: providing a carbon black product; pulverizing the carbon
black product to a desired particle size using a pulverizer; classifying
the pulverized carbon black using a classifier; magnetically separating a
quantity of ferrous material from the carbon black product to make the
carbon black product substantially metal-free; supplying the pulverized,
classified, and substantially metal free carbon black product to a
pelletization subsystem; and pelletizing the pulverized, classified, and
substantially metal free carbon black product using the pelletization
subsystem.

15. The method according to claim 14, wherein the step of providing the
carbon black product includes the steps of: depositing a quantity of
waste into a porous container, the porous container adapted to allow at
least one convective stream of substantially anaerobic gas to flow
therethrough; inserting the porous container into a pyrolysis thermal
processor; sealing the thermal processor; circulating the at least one
convective stream of gas in the pyrolysis thermal processor; heating the
waste with the convective stream of gas according to a time-temperature
profile to form the carbon black product; cooling the carbon black
product by circulating the at least one convective stream of gas through
a cooler; and collecting the carbon black product.

16. The method according to claim 14, wherein the step of pelletizing the
pulverized, classified, and substantially metal free carbon black product
using the pelletization subsystem further includes the steps of:
injecting a binder oil into a mixer in a desired amount; and mixing the
carbon black product and the binder oil in the mixer, wherein the
pelletized carbon black product is formed.

17. The method according to claim 14, further comprising the step of
bagging the pelletized carbon black product for at least one of handling,
storing, and shipping.

18. The method according to claim 14, wherein the step of pulverizing the
carbon black product reduces the carbon black product to about 325 mesh
particles.

19. The method according to claim 18, wherein up to 99.99% of the
pulverized carbon black product passes through a 325 mesh screen.

20. The method according to claim 14, wherein the step of pelletizing the
pulverized, classified, and substantially metal free carbon black product
using the pelletization subsystem results in a pelletized carbon black
product having an average diameter from about 0.125 inches to about
0.0625 inches.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of U.S. patent application Ser.
No. 12/121,339, filed on May 15, 2008, which in turn claims priority to
U.S. Provisional Patent Application No. 60/938,480, filed May 17, 2007.
The entire disclosures of the above applications are hereby incorporated
herein by reference.

FIELD OF THE INVENTION

[0002] The present disclosure relates to waste recycling and, more
particularly, to processes for pelletizing carbon black products produced
by pyrolysis of waste materials.

BACKGROUND OF THE INVENTION

[0003] The U.S. Environmental Protection Agency (EPA) estimates that
approximately 250 million scrap tires are generated in the United States
each year. In the United States alone, the Rubber Manufacturers
Association (RMA) has estimated that between two and three billion scrap
tires currently reside in landfills or are otherwise stockpiled. Waste
tires take up a significant amount of space in landfills, and burying of
the tires can lead to landfill contamination. Stockpiling waste tires
provides breeding grounds for pests and represents a significant fire
hazard. Burning of tires causes a significant amount of air pollution,
and run-off from tire fires can contaminate ground water. The handling
and disposal of waste tires is a significant environmental problem, and
the desirability of recycling waste is evident.

[0004] One method of recycling waste tires is pyrolysis. Known tire
pyrolysis processes include heating tires to produce useful products such
as oils, gases, recyclable metals, and carbonaceous char. As disclosed in
U.S. Pat. Nos. 5,783,046, 6,372,948, and 7,037,410 to Flanigan, the
entire disclosures of which are hereby incorporated herein by reference,
a known pyrolysis process includes heating rubber in the substantial
absence of oxygen to a temperature sufficient to pyrolyze the rubber,
distilling a vapor comprising hydrocarbon from the rubber, and producing
a solid carbonaceous char. Weinecke et al. in U.S. Pat. No. 7,101,463,
hereby incorporated herein by reference in its entirety, describes a
system and process for the recovery of oil from shredded vehicle tires
that utilizes a pair of sequentially positioned packed towers. Also
disclosed in U.S. Pat. No. 5,894,012 to Denison, hereby incorporated
herein by reference in its entirety, is a waste processing system that
produces clear and colorless oil for use in rubber and plastic
applications and a carbonaceous char equivalent to a low structure
furnace black.

[0005] The carbonaceous char produced from typical pyrolysis processes is
generally a friable material. The carbonaceous char can be reduced to
finely-divided particles or "fluff" form through known pulverization
techniques. However, a mixing and dispersion of finely-divided particles
of carbonaceous char into rubber and plastics is known to be problematic.

[0006] A variety of methods for converting individual particles of carbon
black into pellets for improved mixing and dispersion are known to the
art. For example, a finely-divided carbon black may be agitated under dry
conditions in such a manner as to reduce the quantity of air or other
gases associated with the carbon black and cause a degree of
agglomeration of the discrete particles of the carbon black. Under wet
conditions, the finely-divided carbon black may be agitated in a wet
pelletizer in the presence of sufficient liquid pelletizing medium, such
as water or a dilute aqueous solution of a binder such as sugar,
molasses, dextrin, starch, calcium lignin sulfonate, and the like, to
permit agglomeration of the individual particles into free-flowing
pellets of suitable structural strength and stability. However, the
application of standard carbon black dry and wet pelletization techniques
to carbonaceous char from pyrolysis processes has not provided a
desirable pelletization quality.

[0007] There is a continuing need for a system and method of converting a
carbonaceous char from a pyrolysis process to a free-flowing pelletized
form in order to permit inexpensive and convenient handling, storing and
shipping thereof. Desirably, a carbon black product produced from the
carbonaceous char is provided in a form convenient for use by
manufacturers of rubber, plastics, and other commercial products.

SUMMARY OF THE INVENTION

[0008] In concordance with the instant disclosure, a system and method of
converting a carbonaceous char from a pyrolysis process to a free-flowing
pelletized form in order to permit inexpensive and convenient handling,
storing and shipping thereof, and a carbon black product produced from
the carbonaceous char in a form convenient for use by manufacturers of
rubber, plastics, and other commercial products, is surprisingly
discovered.

[0009] In one embodiment, a system for preparing a pelletized carbon black
product includes a mixer in communication with a source of carbon black
product, such as a carbonaceous char. The mixer is configured to receive
the carbon black product. The system also includes a binder oil storage
tank in fluid communication with the mixer. The binder oil storage tank
is configured to inject a desired amount of a binder oil into the mixer
with the carbon black product to pelletize the carbon black product.

[0010] In a further embodiment, a method for preparing a pelletized carbon
black product comprises the steps of: providing a carbon black product;
supplying the carbon black product to a mixer; injecting a binder oil
into the mixer in a desired amount; and mixing the carbon black product
and the binder oil, wherein the pelletized carbon black product is
formed.

[0011] In another embodiment, a pelletized carbon black product includes a
carbon black product in an amount greater than about 85 percent by weight
relative to the total weight of the pelletized carbon black product. The
carbon black product includes a carbon black in an amount between about
65 percent and about 98 percent, an organic volatile material in an
amount between about 1 percent and about 20 percent, and an inorganic ash
in an amount in an amount up to about 15 percent. All percentages are by
weight relative to the total weight of the carbon black product. The
pelletized carbon black product further includes a binder oil in an
amount sufficient to agglomerate the carbon black product into
substantially free-flowing pellets.

DRAWINGS

[0012] The above, as well as other advantages of the present disclosure,
will become readily apparent to those skilled in the art from the
following detailed description, particularly when considered in the light
of the drawing described hereafter.

[0013] The drawing is a process flow diagram depicting a system for
pelletizing a carbonaceous char from a pyrolysis process.

DETAILED DESCRIPTION OF THE INVENTION

[0014] The following description is merely exemplary in nature and is not
intended to limit the present disclosure, application, or uses. It should
also be understood that throughout the drawings, corresponding reference
numerals indicate like or corresponding parts and features. In respect of
the methods disclosed, the order of the steps presented is exemplary in
nature, and thus, is not necessary or critical.

[0015] The present disclosure includes a system 2 and method for
pelletizing a carbon black product 4 formed from a carbonaceous char
produced by pyrolysis of whole tires, tire shreds, waste feedstocks,
waste plastic feedstocks, medical waste, and the like. An exemplary
pyrolysis process is disclosed in Assignee's copending U.S. application
Ser. No. 12/121,139, filed May 15, 2008, hereby incorporated herein by
reference in its entirety. A skilled artisan should understand, however,
that the present system 2 and method may be employed with the carbon
black product 4 produced by another pyrolysis system and process, as
desired.

[0016] As shown in FIG. 1, the system 2 includes a source 6 of the carbon
black product 4. The source 6 may be a post-pyrolysis processing system
configured to separate a quantity of extraneous materials, such as
fiberglass and metals, from the carbon black product 4 following
pyrolysis of the waste, for example. A mixer 8 is in communication with
the source 6 of carbon black product 4. The mixer 8 is configured to
selectively receive the carbon black product 4 from the source 6, as
desired.

[0017] The system 2 further includes a binder oil storage tank 10 in fluid
communication with the mixer 8. The binder oil storage tank 10 is
configured to selectively inject a desired amount of a binder oil 12 into
the mixer 8 when the carbon black product 4 is disposed therein. The
binder oil tank 10 may have at least one heater 13 coupled thereto for
heating the binder oil 12 to a desired temperature. It should be
understood that the agitation and mixing of the carbon black product 4
and the binder oil 12 by the mixer 8 is sufficient to form a pelletized
carbon black product 14 according to the present disclosure.

[0018] In certain embodiments, the mixer 8 is one of a batch drum mixer
and a rollo-mixer, for example. It should be understood that more than
one mixer 8 may be employed in the system 2. The mixer 8 generally is
employed to admix the carbon black product 4 and the binder oil 12 and
cause the carbon black product 4 to agglomerate into the pelletized
carbon black product 14. The mixer 8 may rotate at a rate of up to about
500 RPM, for example. In another example, the mixer 8 is heated to a
temperature from about 40° F. to about 200° F. to
facilitate the admixing of the carbon black product 4 with the binder oil
12. A skilled artisan should appreciate that other suitable mixers and
mixer parameters may be employed as desired.

[0019] In particular embodiments, the system 2 further includes a
pulverizer 16. The pulverizer 16 is configured to reduce the carbon black
product 4 to a desired particle size. For example, the pulverizer 16 may
reduce the carbon black product 4 to about 325 mesh particles. The
average particle size of the carbon black product 4 may be about five
microns, although it should be appreciated that a range of particle sizes
may be produced as desired. In particular, favorable results have been
obtained when up to 99.99% of the pulverized carbon black product 4
passes through a 325 mesh screen. As a nonlimiting example, the
pulverizer 16 is a roller mill pulverizer. Other suitable pulverizers 16
may also be employed.

[0020] The pulverizer 16 is disposed between the source 6 of the carbon
black product 4 and the mixer 8. The pulverizer 16 is configured to
pulverize the carbon black product 4, generally provided as large friable
portions from the pyrolysis process, to the desired particle size. The
pulverizer 16 may have a pulverizer feed bin 17, for example, which is
adapted to selectivity feed the carbon black product 4 to the pulverizer
16. The carbon black product 4 may be gravity fed to the pulverizer 16
from the pulverizer feed bin 17. In other embodiments, the carbon black
product 4 is fed to the pulverizer 16 by a mechanized means, such as a
moving belt, screw, or the like.

[0021] The pulverizer 16 is further in communication with the mixer 8 and
configured to provide the pulverized carbon black product 4 to the mixer
8 as desired. The carbon black product 4, when pulverized, may be
pneumatically transferable by air conveyance, for example, in conjunction
with an air compression system (not shown). A skilled artisan should
understand that other means for transferring the carbon black product 4
through the system 2 may also be employed.

[0022] In a further embodiment, the system 2 includes a classifier 18. The
classifier 18 is configured to selectively provide the carbon black
product 4 of the desired particle size to the mixer 8, as desired. The
classifier 18 is disposed between the pulverizer 16 and the mixer 8. The
classifier 18 may be employed to separate extraneous material, such as
fiberglass, from the carbon black product 4. The classifier 18 may be an
air classification unit, for example. A commercially available air
classification unit designed for operation at rotor speeds from about 400
RPM to about 2,000 RPM is the Micro-Sizer® air classification system,
manufactured by Progressive Industries, Inc. of Sylacauga, Ala. One of
ordinary skill should appreciate that other classifiers 18 may also be
used.

[0023] It should be appreciated that the carbon black product 4, following
pulverization, may be collected and stored in a collection unit 19 for
batch production of the pelletized carbon black product 14. As a
nonlimiting example, the collection unit 19 may be a product collection
cyclone or centrifugal collector as is known in the art. The product
collection cyclone may use cyclonic action to separate the carbon black
product 4 from an air carrier stream, for example. The centrifugal force
created by cyclonic action throws the carbon black product 4 toward the
wall of the product collection cyclone. After striking the wall, carbon
black product 4 falls into a hopper located underneath the area of
cyclonic action. It should be further understood that other suitable
collection units 19 may also be employed.

[0024] The system 2 according to the present disclosure may further
include a magnetic separator 20 configured to separate extraneous ferrous
material from the carbon black product 4. As a nonlimiting example, the
pulverized carbon black product 4 may be metered over the magnetic
separator 20 to remove recyclable metal, such as steel belt wire from
tires employed in the pyrolysis process, prior to the pelletization of
the carbon black product 4. In particular embodiments, the magnetic
separator 20 is a rotating magnetic drum. The magnetic separator 20 is
disposed between the source 6 of carbon black product 4 and the mixer 8.
The magnetic separator 20 may provide a substantially metal-free carbon
black product 4 for delivery to the mixer 8.

[0025] The system 2 may further include a pellet bagger 22 as is known in
the art. The pellet bagger 22 is in communication with the mixer 8. The
pellet bagger 22 is configured to bag the pelletized carbon black product
14 produced by the mixer 8 for at least one of handling, storing and
shipping. As a nonlimiting example, the pellet bagger 22 is configured to
fill a supersack with the pelletized carbon black product 14. The pellet
bagger 22 is in communication with a discharge conveyor 24 that delivers
the bagged pelletized carbon black 14 to a storage system 26 for storing
the pelletized carbon black 14 prior to an end use. Other suitable
containers for handling, storing, and shipping the pelletized carbon
black product 14 may also be filled. In one alternative embodiment, the
system 2 may be adapted to feed the pelletized carbon black 14 directly
to a rail car or container, for example, as desired.

[0026] The present disclosure further includes a method for preparing the
pelletized carbon black product 14. The method includes the steps of
providing the carbon black product 4 and supplying the carbon black
product 4 to the mixer 8. The binder oil 12 is injected into the mixer 8
in a desired amount. The carbon black product 4 and the binder oil 12 are
admixed to thereby form the pelletized carbon black product 14.

[0027] As described hereinabove, the carbon black product 4 is typically a
carbonaceous char produced during pyrolysis of a waste material, such as
waste tires. In a particular embodiment, the carbon black product 4 is
provided by a pyrolysis process as disclosed in Assignee's copending U.S.
application Ser. No. 12/121,139. For example, the pyrolysis process
includes the step of depositing a quantity of waste into a porous
container, the porous container adapted to allow at least one convective
stream of substantially anaerobic gas to flow therethrough. The porous
container is inserted into a pyrolysis thermal processor. The thermal
processor is sealed and at least one convective stream is circulated
therethrough. The waste is heated with the convective stream of gas
according to a time-temperature profile to pyrolyze the waste and produce
the carbon black product 4. The convective stream of gas is then
circulated through a cooler to cool the carbon black product 4. The
carbon black product 4 is subsequently collected for pelletization in the
mixer 8.

[0028] The method further includes the step of pulverizing the carbon
black product 4 to a desired particle size prior to supplying the carbon
black product 4 to the mixer 8. As described hereinabove, a quantity of
extraneous material may also be separated from the carbon black product 4
with at least one of the classifier 18 and the magnetic separator 20
prior to supplying the carbon black product 4 to the mixer 8. In a
particular embodiment, the separation includes magnetically separating
the quantity of ferrous material from the carbon black product 4 to
provide the substantially metal-free carbon black product 4.

[0029] The admixing of the carbon black product 4 and the binder oil 12
according to the method of the present disclosure produces the pelletized
carbon black product 14. It should be appreciated that the carbon black
of the carbon black product 4 includes a substantially amorphous carbon.
The carbon black product 4 may include carbon black in an amount between
about 65 percent and about 98 percent. The carbon black product 4 further
includes an organic volatile material in an amount between about 1
percent and about 20 percent. The carbon black product 4 also includes an
inorganic ash in an amount up to about 15 percent. All percentages are by
weight relative to the total weight of the carbon black product 4. The
inorganic ash may include elemental zinc from zinc oxides originally used
in the waste rubber as an activator, and inorganic fillers employed in
the waste rubber, such as silica and clays, for example. In certain
embodiments, the inorganic ash may include a quantity of elemental
sulfur, for example, that was employed to originally vulcanize waste
rubber.

[0030] As a further nonlimiting example, the carbon black product 4 may
include between about 85 percent and about 95 percent carbon black and
about 1 percent to about 15 percent residual volatiles in the form of
residual polymer and hydrocarbons remaining at the end of the pyrolysis
process. The carbon black product 4 also may include an inorganic ash in
an amount up to about 9 percent to about 12 percent. It is surprisingly
found that the residual volatiles advantageously minimize dusting of the
pelletized carbon black product 14 and facilitate dispersion and
miscibility of the pelletized carbon black product 14 in elastomer and
oil applications.

[0031] The pelletized carbon black product 14 has the binder oil 12 in an
amount sufficient to provide a pelletized carbon black product 14 with a
pellet hardness and fines content suitable for use in rubber mixing, for
example. Pellets must have a sufficient strength to resist physical break
down during transportation, but also facilitate dispersion in rubber and
plastic compounds. Fines are considered an indicator of bulk handling and
rubber and plastic mixing difficulties. The pelletized carbon black
product 14 may have a pellet hardness of up to about 40 gf, as a
nonlimiting example. As the binder employed to pelletize the carbon black
product 4 an oil, it should be appreciated that the pelletized carbon
black product 14 is substantially non-dusting and may have minimal fines
content. The amount of the binder oil 12 may be selected to provide a
desirable fines content and level of non-dusting as desired.

[0032] As a nonlimiting example, the binder oil 12 may be used in an
amount up to about 15 percent by weight relative to the total weight of
the pelletized carbon black product 14. In particular embodiments, the
binder oil 12 in an amount of about 12.5 percent by weight relative to
the total weight of the pelletized carbon black product 14 is sufficient
to form pellets with the desired characteristics. As nonlimiting
examples, the binder oil 12 is at least one of a highly aromatic oil, a
naphthenic oil, and a paraffinic oil. It should be appreciated that
product oil derived from the pyrolysis process may also be used as a
binder oil 12. A skilled artisan may select other suitable binder oils 12
and levels as desired.

[0033] Individual pellets of the pelletized carbon black product may have
an average diameter from about 0.125 inches to about 0.0625 inches, for
example. In other embodiments, the pellets produced according to the
present method may fall within a desired range of about 18 to about 60
mesh, for example. The individual pellets of the pelletized carbon black
product 14 may be substantially spherical, although one of ordinary skill
in the art should understand that the pelletized carbon black product 14
may be provided other shapes that facilitate flowability of the
pelletized carbon black product 14. The pelletization process minimizes
product dusting, and improves density and flow properties associated with
the carbon black product 4 produced by pyrolysis of waste. The pelletized
carbon black product 14 may then be stored, for example, in a silo,
supersack or in small bags for delivery and the desired end use.

[0034] It should be appreciated that the pelletized carbon black product
14 according to the present disclosure provides for an optimized
dispersion and miscibility of the carbon black product 4 in rubber and
plastic compounds, particularly in comparison to known pyrolysis products
provided in fluff form. It is surprisingly found that the use of the
binder oil 12, in conjunction with the residual volatiles of the
pelletized carbon black product 4, advantageously minimizes dusting of
the pelletized carbon black product 14.

[0035] While certain representative embodiments and details have been
shown for purposes of illustrating the invention, it will be apparent to
those skilled in the art that various changes may be made without
departing from the scope of the disclosure, which is further described in
the following appended claims.